Exclusion seals are primarily used to keep dirt and other contaminants from passing into bearings and other sensitive areas. Some of the devices that fall within the exclusion seals category do not actually have any sealing capabilities. Instead, they serve to wipe or scrape away debris from moving or reciprocating shafts or rods. This helps to protect the seal and extend its life.
Exclusion seals are available in three main configurations, V-ring, wipers, and scrapers.
V-ring seals are all rubber seals used primarily to exclude dirt and other contaminants. V-rings stretch over a shaft and make a seal against the side of a housing or other machine component. Wipers are flexible lip exclusion seals. They are used to wipe contaminants from a shaft. Some wipers also act as seals. Scraper exclusion seals have a scraping edge that maintains contact with the rod regardless of any rod deflection or motion. The lip of the scraper is shaped with a semi-rigid leading edge that removes any contamination from the sealing area. Scrapers have no real sealing capabilities.
How to Select
When selecting between available exclusions seals, it is important to be aware of both the operating dimensions needed for the seal, and the performance stress to which it will be subjected. Important specifications to consider include the I.D. and O.D. of the exclusion seal and the O.D. of the housing bore to which it will be applied. Other important considerations include the axial cross section and radial cross section of the seal, and finally the gland width into which the exclusion seal will be mounted.
What to Consider When Selecting
Service limits to consider when working with exclusion seals include the temperature range through which the seals will need to perform, and any fluids with which they may come in contact. Both of these situations bear consideration, as they will help to determine the best material construction for the exclusion seals. Additional concern should be paid to the pressures, vibration or shaft speed, to which the exclusion seals will be subjected, and whether they will be needed in vacuum rated applications.
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